Design of skin reinforcement for concrete pile caps

• Autorzy: de Araujo J. M.
• Języki publikacji: EN

Abstrakty

EN

The large pile caps of buildings and bridges may get superficial cracks already in the early hours after concreting. Due to the large volume of concrete, the temperature inside the pile cap may reach very high values, as a result of the heat of hydration of cement. Because of the strong temperature gradients, the surface of the pile cap is tensioned and may crack. The employment of skin reinforcement does not avoid the cracking of concrete. However, this reinforcement may reduce the crack width, providing the onset of a large number of small cracks, instead of a single crack with large opening. The object of this work is to address this issue by analyzing the main variables involved and suggest a design methodology for the calculation of skin reinforcement of concrete pile caps.

PL

W dużych oczepach fundametnów palowych budynków i mostów już po kilku godzinach od zabetonowania mogą pojawić się rysy powierzchniowe. Z powodu znacznej objętości betonu, w wyniku ciepła wyprodukowanego w procesie hydratacji cementu, temperatura wewnątrz takiego oczepu może osiągnąć znaczą wartość. Na skutek znacznych gradientów temperatury powierzchnia oczepu poddawana jest rozciąganiu i może ulec zarysowaniu. Zastosowanie zbrojenia przypowierzchniowego nie pozwala uniknąć zarysowania betonu. Zbrojenie to może jednak ograniczyć szerokość rozwarcia rys poprzez zapewnienie powstania licznych, ale małych rys zamiast znacznej pojedynczej rysy. Przedmiotem tej pracy jest odniesienie się do tego zagadnienia poprzez analizę głównych czynników oraz propozycję metodologii obliczania zbrojenia przypowierzchniowego w betonowych oczepach pali.

Słowa kluczowe

EN

concrete; cracking; heat transfer; pile cap; reinforcement; thermal stress

PL

cement; pękanie; przepływ ciepła; oczep pala; zbrojenie; naprężenie cieplne

• Wydawca: Silesian University of Technology
• Czasopismo: Architecture Civil Engineering Environment
• Rocznik: 2014
• Tom: Vol. 7, no. 4
• Strony: 29--38
• Opis fizyczny: Bibliogr. 18 poz.

Twórcy

autor

de Araujo J. M.

• Engineering School, Federal University of Rio Grande, Av. Itália, km 8, Campus Carreiros, Rio Grande, RS, 96203-900, Brazil

Bibliografia

• [1] BS 8007:1987; Code of practice for Design of concrete structures for retaining aqueous liquids. London, UK; 1987
• [2] Harrison T. A.; Early-age Thermal Crack Control in Concrete, CIRIA Report 91, London, UK; 1992
• [3] EN 1992-3:2006; Eurocode 2: Design of Concrete Structures – Part 3: Liquid retaining and containment structures, Brussels, Belgium; 2006
• [4] Bamforth P.; Early-Age Thermal Crack Control in Concrete, CIRIA Report C660:2007, London, UK; 2007
• [5] Flaga K., Furtak K.; Problem of thermal and shrinkage cracking in tanks vertical walls and retaining walls near their contact with solid foundation slabs, Architecture Civil Engineering Environment, Vol.2, No.2, 2009; p.23-30
• [6] Bamforth P., Denton S., Shave J.; The development of a revised unified approach for the design of reinforcement to control cracking in concrete resulting from restrained contraction, Report ICE/0706/012, London, UK; 2010
• [7] EN 1992-1-1:2010; Eurocode 2: Design of concrete structures – Parte 1-1: General rules and rules for buildings, Brussels, Belgium; 2010
• [8] CEB-FIP Model Code 1990. Thomas Telford, London, UK; 1993
• [9] ACI 318M-11:2011; Building Code Requirements for Structural Concrete (ACI 318M-11) and Commentary. USA, ACI, 2011
• [10] fib Model Code for Concrete Structures 2010. Ernst & Sohn, Berlin, Germany; 2013
• [11] Zienkiewicz O. C., Taylor R. L.; The Finite Element Method. 7nd ed. Butterworth-Heinemann, London, UK; 2013
• [12] Araújo J. M.; Analysis of concrete gravity dams considering the construction phase and the dynamic interaction dam-reservoir-foundation. Doctoral thesis, Federal University of Rio Grande do Sul, Porto Alegre, Brazil; 1995
• [in Portuguese]
• [13] Araújo J. M., Awruch A. M.; Cracking safety evaluation on gravity concrete dams during the construction phase. Computers and Structures, Vol.66, No.1, 1998; p.93-104
• [14] Japan Society of Civil Engineers; Standard Specifications for Concrete Structures – 2007, Design, JSCE Guidelines for Concrete No.15, Tokyo, Japan; 2010
• [15] Serth R. W.; Process Heat Transfer. Principles and Applications. Academic Press, Burlington, USA; 2007
• [16] Andrade W. P., Fontoura J. T. F., Bittencourt R. M., Guerra E. A.; Adiabatic temperature rise of concrete. Bulletin IBRACON M-4, São Paulo, Brasil; 1981
• [in Portuguese]
• [17] Klemczak B., Knoppik-Wróbel A.; Early age thermal and shrinkage cracks in concrete structures – influence of geometry and dimensions of a structure. Architecture Civil Engineering Environment, Vol.4, No.3, 2011; p.55-70
• [18] Atrushi D. S.; Tensile and Compressive Creep of Early Age Concrete: Testing and Modelling. Doctoral Thesis, Norwegian University of Science and Technology, Trondheim, Norway; 2003